1. The problem statement, all variables and given/known data Let f(x)=lim (csct-cscx)/t-x. Find the value of f'(pi/4) t-x 2. Relevant equations f(x)-f(a)/x-a 3. The attempt at a solution I tried doing it from first principles but couldn't figure out how to get rid of h. I also tried doing L'hopital's rule and got root2 but I know the answer is 3root2. I also tried making the equation (cscx-root2)/x-(pi/4). Nothing seems to work!